March 17th, 2021 | Company News
What is Particle Imaging Velocimetry?
Particle imaging velocimetry is a laser optical measurement technique which is non-intrusive and is used in research and diagnostics for flow turbulence, microfluidics, spray atomization and combustion processes. Particle imaging velocity measures the entire region within the flow as its velocity is measured simultaneously.
The basic principle includes photographic recording of the motion of microscopic particles that follow the fluid or gas flow. Image processing techniques are then employed to ascertain the particle motion, the flow velocity, from the photographic recordings. As long as there are enough particles inside the area of flow being examined, the complete velocity field of the flow can be ascertained.
This highlights the differences between particle imaging velocimetry and point measurement methods which use probes to measure flow velocity at a single point. The main benefit of particle imaging velocimetry is that it is a quantitative flow field mapping method which can offer physical insight into the complete flow behavior. Particle imaging velocimetry enables both the extraction of measurement data and the visualization of flow structures.
The standard particle image velocimetry set up is made up of a high-speed camera, a high-power multi-pulsed laser, and an optical arrangement to transform laser output light to a light sheet and a synchronizer which controls the synchronization of the laser and the camera.
What is Particle Imaging Velocimetry Used For?
Particle image velocimetry is used in aerodynamics and fluid mechanics as an experimental tool. As it offers a near-instantaneous velocity field, particle imaging velocimetry offers the benefits of a flow visualization technique whilst also offering critical quantitative information. When the velocity field has been ascertained, data like vorticity and strain can be easily found along with the turbulence intensity.
In aerodynamics, particle imaging velocimetry is helpful in understanding unsteady flow phenomena. It can be used for measurement of aircraft wake vortices of a lifting wing, investigation of rotor aerodynamics with noise emission of a range of noise sources and transonic flow over airfoils. This is a growing area of interest as airports reach higher capacities and takeoffs and landings become more frequent. Particle imaging velocimetry is important to understand the efficiency of airports.
Wake vortex effects have also caused numerous aircraft mishaps, which is why non-intrusive optical flow measurement methods such as particle imaging velocimetry are growing in importance.
Particle Imaging Velocimetry is also employed in the investigation of liquid flows, which is the vortex-free-surface interaction, thermal convection and Couette flow between concentric spheres.